Teams: 2 players per team.
Starting Life: 60 life per team.
Commander Damage: Commander damage is tracked separately for each player. A player who takes 21 or more combat damage from the same commander loses the game.
Turns: Teammates share a turn:
Draw together
Main phases together
Combat together
End step together
Deck Construction:
100-card Commander decks
Normal Commander deck-building rules apply
Teammates may use the same cards unless your event specifies otherwise
Mulligans:
Use the normal Commander free mulligan rule
Each player mulligans independently
Attacking:
Creatures attack the opposing team
Attacking player chooses which opponent each creature attacks
Blocking:
The defending team decides blocks together
Either teammate can block creatures attacking them
Shared Resources:
Teams share life total
Players do not share:
Mana
Hands
Libraries
Graveyards
Command zones